The present invention relates to a computer system having a plurality of computer systems connected to each other. More particularly, the present invention relates to a computer system having a plurality of computers connected to each other, wherein each computer controls access to a shared memory based on structural definition information which describes a structure of the computer system and wherein the computer system may be a loosely-coupled computer system.
Loosely-coupled computer systems which share hard disks so as to share data have been proposed. In order to implement such systems a plurality of hard disk controllers and an attachment for connecting hard disks to be shared are required.
Examples of apparatus for implementing hard disk sharing by SCSI Profile of Fibre Channel is described in The VAXcluster Concept: An Overview of a Distributed System, by Nancy P. Kronenberg et. al., Digital Technical Journal, No.5 September 1987, pp 7-21, and examples of apparatus for implementing Fibre Channel Small Computer System Interface (SCSI) Profile which has been standardized in ANSI, is described in Implementing a Fibre Channel SCSI Transport, by Robert Snively, IEEE COMPCON, Spring 1994, pp 78-82 have been proposed.
Examples of apparatus implementing a Network File System (NFS) is described in DISTRIBUTED SYSTEMS, by George F. Coulouris et. al., pp 391-407, 1991 as a means for realizing file sharing by Remote Procedure Call (RPC) in a loosely-coupled computer system has also been proposed.
In Fibre Channel, when the shared hard disks are accessed, access is required to be conducted through the attachment. Thus, the increased access to the attachment causes the reduction of performance, the performance reduction is a serous disadvantage.
A System is a system which uses other processors for performing processing operations based upon the request of another processor. RPC provides for communications between processors to cause other processors to execute processing for another processor. Thus, soft overhead increases. Increased soft overhead causes a reduction in the performance of the system. The reduced performance is a disadvantage.